I need something made out of stone or concrete, what kind of service or company should I be looking for?

I have a design for an item I would like to have made out of stone or concrete. I’d probably want around 100. I have a drawing of the item – it is detailed. I Googled stone and concrete molders but emailed a bunch and they don’t seem to do this kind of work. Is there a special name for companies that will manufacture items for me made out of stone or concrete? The item is a fairley simple shape, pretty much just a rectangular box that sits on a plate.